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Ultrafast dynamics of material excitation of dielectrics with ultrashort pulsed Bessel beams

: Kalupka, C.; Holtum, T.; Reininghaus, M.


Klotzbach, U. ; Society of Photo-Optical Instrumentation Engineers -SPIE-, Bellingham/Wash.:
Laser-based Micro- and Nanoprocessing XII : 30 January-1 February 2018, San Francisco, California, United States
Bellingham, WA: SPIE, 2018 (Proceedings of SPIE 10520)
ISBN: 978-1-5106-1525-0
ISBN: 978-1-5106-1526-7
Paper 105200G, 8 S.
Conference "Laser-Based Micro- and Nanoprocessing" <12, 2018, San Francisco/Calif.>
Fraunhofer ILT ()

We report on the dynamics of the excitation process of dielectrics using a spatial Bessel beam intensity distribution with pulse durations below 10 ps. The generated free-electron plasma is analyzed by time-resolved transversal pump-probe shadowgraphy on a timescale up to 20 ps after initial excitation. Our measurements reveal the ultrafast generation of the free-electron plasma, which reaches a maximum after approximately 10 ps. The subsequent relaxation is comparable slow with a time constant in the range of 100 ps. We perform measurements with different pump pulse durations in the range from 0.1 ps up to 9 ps and observe that the spatial distribution of the generated free-electron plasma strongly depends on the pulse duration and pulse energy. Our results show that the spatial distribution of the free-electron plasma can be controlled by a coarse adjustment of the pulse parameters. The understanding of the correlation of the spatial energy deposition and pulse parameters is useful for a high precision and fast glass cutting process.